1. Field of the Invention
The present invention relates to a printing apparatus in which the temperature of a printhead is detected, a method of correcting in the printing apparatus and a storage medium storing a program for performing the correction.
2. Description of the Related Art
In general, since an ink-jet printing apparatus prints by discharging ink from a printhead, it is important that the amount of ink discharged be made constant in order to stabilize print density. Since the temperature of the ink changes owing to the fact that heat from the surrounding environment or from the printhead acts upon the ink, the viscosity of the ink varies. It is known that the amount of ink discharged varies as a result of this variation in viscosity. Accordingly, control for maintaining temperature is performed in such a manner that the temperature of the printhead will remain constant. Further, control is exercised so as to hold the amount of discharged ink constant as by measuring the temperature of the printhead (which is equivalent to measuring the ink temperature) and controlling the head driving signal in accordance with the temperature measured. In order to accomplish this, it is vital that the temperature of the printhead be measured accurately. The specification of Japanese Patent Laid-Open No. 2001-63028 describes a method of reading printhead temperature by providing an amplifier, which amplifies the output of a temperature sensor, on a carriage substrate, amplifies the output of the temperature sensor up to a high voltage and then outputs the high-voltage signal.
However, since the foregoing method requires that the amplifier be placed on the carriage substrate, the substrate is of a larger size and higher cost. Further, with the method of detecting printhead temperature by a temperature sensor installed on the printhead, there is an issue that must be taken into account in order to achieve real-time detection of temperature during a printing operation. Specifically, it is necessary to prevent a decline in detection accuracy ascribable to the effects of wiring crosstalk, which is a consequence of a data transfer signal for the purpose of driving the printhead, and the effects of crosstalk resulting from the printhead driving voltage at the time of printing.